Biological and clinical characterization of paclitaxel poliglumex (PPX, CT-2103), a macromolecular polymer-drug conjugate

Particle replication in nonwetting templates nanoparticles with tumor selective alkyl silyl ether docetaxel prodrug reduces toxicity

Delivery systems designed to have triggered release after passively targeting the tumor may improve small molecule chemotherapeutic delivery. Particle replication in nonwetting templates was used to prepare nanoparticles to passively target solid tumors in an A549 subcutaneous xenograft model. An acid labile prodrug was delivered to minimize systemic free docetaxel concentrations and improve tolerability without compromising efficacy.

Science and technology of the emerging nanomedicines in cancer therapy: A primer for physicians and pharmacists

Nanomedicine, the medical applications of devices based on nanotechnology, promises an endless range of applications from biomedical imaging to drug and gene delivery. The size range of the nanomaterials is strictly defined as 1–100 nm, although many marketed nanomedicines are in the submicron range of 100–1000 nm. The major advantages of using nanomaterials as a carrier for anticancer agents are the possibility of targeted delivery to the tumor; their physical properties such as optical and magnetic properties, which can be exploited for developing contrast agents for tumor imaging; their ability to hold thousands of molecules of a drug and deliver at the required site and also the ability to overcome solubility and stability issues. Currently, there are several nanotechnology-enabled diagnostic and therapeutic agents undergoing clinical trials and a few already approved by Food and Drug Administration. Targeted delivery of anticancer agents is achieved by exploiting a unique characteristic of the rapidly dividing tumor cells called “the enhanced permeability and retention effect.” Nanoparticles with mean diameter between 100 and 200 nm or even above 200 nm have also been reported to be taken up by tumor cells via the enhanced permeability and retention effect. In addition to this passive targeting based on size, the nanoparticle surface may be modified with a variety of carefully chosen ligands that would interact with specific receptors on the surface of the tumor cells, thus imparting additional specificity for active targeting. Regional release of a drug contained in a nanoparticulate system by the application of external stimuli such as hyperthermia to a thermosensitive device is another innovative strategy for targeted delivery. Nanoparticles protect the enclosed drug from rapid elimination from the body, keep them in circulation for prolonged periods and often evade expulsion by the efflux pump mechanisms, which also leads to avoidance of development of resistance. This review focuses on the science and technology of Food and Drug Administration–approved cancer nanomedicines such as Abraxane, Doxil, DaunoXome and those drug-delivery systems that have reached an advanced stage of clinical development utilizing liposomes, albumin nanospheres, thermosensitive devices and gold nanoshells.

Validation of tumour models for use in anticancer nanomedicine evaluation: the EPR effect and cathepsin B-mediated drug release rate

Purpose

Intravenously (i.v.) administered nanomedicines have the potential for tumour targeting due to the enhanced permeability and retention (EPR) effect, but in vivo tumour models are rarely calibrated with respect to functional vascular permeability and/or mechanisms controlling intratumoural drug release. Here the effect of tumour type and tumour size on EPR-mediated tumour localisation and cathepsin B-mediated drug release was studied.

Methods

Evans Blue (10 mg/kg) and an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer–doxorubicin (Dox) conjugate (FCE28068) (5 mg/kg Dox-equiv) were used as probes and tumour levels (and Dox release) measured at 1 h after i.v. administration in a panel of murine and human xenograft tumours.

Results

Evans Blue and FCE28068 displayed similar tumour levels in the range of 2–18 % dose/g at 1 h for B16F10 and L1210. Approximately half of the tumour models evaluated exhibited tumour size-dependent accumulation of FCE28068; smaller tumours had the highest accumulation. Administration of free Dox (5 mg/kg) produced tumour levels of <2.5 % dose/g independent of tumour size. Whereas the degree of EPR-mediated targeting showed ~12-fold difference across the tumour models evaluated, Dox release from FCE28068 at 1 h displayed ~200-fold variation.

Conclusions

Marked heterogeneity was seen in terms of EPR effect and Dox release rate, underlining the need to carefully calibrate tumour models used to benchmark nanomedicines against known relevant standard agents and for optimal development of strategies for late pre-clinical and clinical development.

Electronic supplementary material

The online version of this article (doi:10.1007/s00280-013-2209-7) contains supplementary material, which is available to authorized users.

Biodegradable multiblock poly(N-2-hydroxypropyl)methacrylamide gemcitabine and paclitaxel conjugates for ovarian cancer cell combination treatment

The synthesis, characterization, and in vitro evaluation of a combination delivery of multiblock poly(N-2-hydroxypropyl)methacrylamide (HPMA), gemcitabine (GEM) and paclitaxel (PTX) conjugates is described in this study. Multiblock copolymer conjugates of a large molecular weight (Mw>200 kDa) were studied and compared to traditional, small molecular weight (Mw<45 kDa) conjugates. Stability of the conjugates in different pH was assessed, and their cytotoxicity in combination toward A2780 human ovarian cancer cells was evaluated by combination index analysis. Treatment duration (4 and 72 h) and sequence of addition were explored. In addition, an HPMA copolymer conjugate with both GEM and PTX in the side chains was evaluated in a similar manner and compared to a physical mixture of individual conjugates. Conjugates with narrow molecular weight distribution (Mw/Mn<1.1) were obtained via RAFT polymerization, and drug loadings of between 5.5 and 9.2 wt% were achieved. Conjugates demonstrated moderate stability with less than 65% release over 24h at pH 7.4, and near complete drug release in the presence of the lysosomal enzyme cathepsin B in 3h. In combination, the cytotoxic effects of a mixture of the conjugates were primarily additive. Synergistic effects were observed when A2780 human ovarian cancer cells were treated simultaneously for 4h with multiblock conjugates (CI<0.7). When both GEM and PTX were conjugated to the same copolymer backbone, moderate antagonism (CI 1.3-1.6) was observed. These results demonstrate that multiblock HPMA copolymer-GEM and -PTX conjugates, when delivered as a mixture of individual agents, are promising for the treatment of ovarian cancer.

The alphabet of intrinsic disorder: II. Various roles of glutamic acid in ordered and intrinsically disordered proteins

The ability of a protein to fold into unique functional state or to stay intrinsically disordered is encoded in its amino acid sequence. Both ordered and intrinsically disordered proteins (IDPs) are natural polypeptides that use the same arsenal of 20 proteinogenic amino acid residues as their major building blocks. The exceptional structural plasticity of IDPs, their capability to exist as heterogeneous structural ensembles and their wide array of important disorder-based biological functions that complements functional repertoire of ordered proteins are all rooted within the peculiar differential usage of these building blocks by ordered proteins and IDPs. In fact, some residues (so-called disorder-promoting residues) are noticeably more common in IDPs than in sequences of ordered proteins, which, in their turn, are enriched in several order-promoting residues. Furthermore, residues can be arranged according to their “disorder promoting potencies,” which are evaluated based on the relative abundances of various amino acids in ordered and disordered proteins. This review continues a series of publications on the roles of different amino acids in defining the phenomenon of protein intrinsic disorder and concerns glutamic acid, which is the second most disorder-promoting residue.

Synthesis and evaluation of a backbone biodegradable multiblock HPMA copolymer nanocarrier for the systemic delivery of paclitaxel

The performance and safety of current antineoplastic agents, particularly water-insoluble drugs, are still far from satisfactory. For example, the currently widely used Cremophor EL®-based paclitaxel (PTX) formulation exhibits pharmacokinetic concerns and severe side effects. Thus, the concept of a biodegradable polymeric drug-delivery system, which can significantly improve therapeutic efficacy and reduce side effects is advocated. The present work aims to develop a new-generation of long-circulating, biodegradable carriers for effective delivery of PTX. First, a multiblock backbone biodegradable N-(2-hydroxypropyl)methacrylamide(HPMA) copolymer-PTX conjugate (mP-PTX) with molecular weight (Mw) of 335 kDa was synthesized by RAFT (reversible addition-fragmentation chain transfer) copolymerization, followed by chain extension. In vitro studies on human ovarian carcinoma A2780 cells were carried out to investigate the cytotoxicity of free PTX, HPMA copolymer-PTX conjugate with Mw of 48 kDa (P-PTX), and mP-PTX. The experiments demonstrated that mP-PTX has a similar cytotoxic effect against A2780 cells as free PTX and P-PTX. To further compare the behavior of this new biodegradable conjugate (mP-PTX) with free PTX and P-PTX in vivo evaluation was performed using female nu/nu mice bearing orthotopic A2780 ovarian tumors. Pharmacokinetics study showed that high Mw mP-PTX was cleared more slowly from the blood than commercial PTX formulation and low Mw P-PTX. SPECT/CT imaging and biodistribution studies demonstrated biodegradability as well as elimination of mP-PTX from the body. The tumors in the mP-PTX treated group grew more slowly than those treated with saline, free PTX, and P-PTX (single dose at 20 mg PTX/kg equivalent). Moreover, mice treated with mP-PTX had no obvious ascites and body-weight loss. Histological analysis indicated that mP-PTX had no toxicity in liver and spleen, but induced massive cell death in the tumor. In summary, this biodegradable drug delivery system has a great potential to improve performance and safety of current antineoplastic agents.

Administration, distribution, metabolism and elimination of polymer therapeutics

Polymer conjugation is an efficient approach to improve the delivery of drugs and biological agents, both by protecting the body from the drug (by improving biodistribution and reducing toxicity) and by protecting the drug from the body (by preventing degradation and enhancing cellular uptake). This review discusses the journey that polymer therapeutics make through the body, following the ADME (absorption, distribution, metabolism, excretion) concept. The biological factors and delivery system parameters that influence each stage of the process will be described, with examples illustrating the different solutions to the challenges of drug delivery systems in vivo.

Antitumor activity of folate-targeted, paclitaxel-loaded polymeric micelles on a human esophageal EC9706 cancer cell line

Background

Esophageal cancer is recognized as one of the most refractory pernicious diseases. In addition, it is an aggressive malignancy with a propensity for local progression and distant dissemination. Because of the poor long-term prognosis for patients with esophageal cancer, increasing attention has focused on the integration of targeted agents into current therapeutics. Nevertheless, there have been few studies reported concerning the therapeutic efficacy of paclitaxel-conjugated polymeric micelles in human esophageal cancer in vivo. Therefore, the aim of this research was to investigate the tumor inhibition effect of composite micelles containing folic acid and paclitaxel on the human esophageal EC9706 cancer cell line.

Methods and results

Intravenous administration of folate-targeted, paclitaxel-loaded micelles was demonstrated to be more efficient in inhibiting subcutaneous xenograft tumors and extending the survival rate of tumor-bearing nude mice than free paclitaxel and plain paclitaxel micelles at an equivalent paclitaxel dose of 20 mg/kg, which was further backed up by flow cytometry, TUNEL, and expression of apoptosis-related proteins, including Bax, Bcl2, and caspase 3 in this study.

Conclusion

The folate-mediated paclitaxel-loaded polymeric micelle is a promising agent for the treatment of human esophageal cancer.

NC-6301, a polymeric micelle rationally optimized for effective release of docetaxel, is potent but is less toxic than native docetaxel in vivo

Drug release rate is an important factor in determining efficacy and toxicity of nanoscale drug delivery systems. However, optimization of the release rate in polymeric micellar nanoscale drug delivery systems has not been fully investigated. In this study NC-6301, a poly(ethylene glycol)-poly(aspartate) block copolymer with docetaxel (DTX) covalently bound via ester link, was synthesized with various numbers of DTX molecules bound to the polymer backbone. The number of DTX molecules was determined up to 14 to achieve an optimal release rate, based upon the authors' own pharmacokinetic model using known patient data. Efficacy and toxicity of the formulation was then tested in animals. When administered three times at 4-day intervals, the maximum tolerated doses of NC-6301 and native DTX were 50 and 10 mg/kg, respectively, in nude mice. Tissue distribution studies of NC-6301 in mice at 50 mg/kg revealed prolonged release of free DTX in the tumor for at least 120 hours, thus supporting its effectiveness. Furthermore, in cynomolgus monkeys, NC-6301 at 6 mg/kg three times at 2-week intervals showed marginal toxicity, whereas native DTX, at 3 mg/kg with the same schedule, induced significant decrease of food consumption and neutrophil count. NC-6301 at 50 mg/kg in mice also regressed a xenografted tumor of MDA-MB-231 human breast cancer. Native DTX, on the other hand, produced only transient and slight regression of the same tumor xenograft. NC-6301 also significantly inhibited growth of OCUM-2MLN human scirrhous gastric carcinoma in an orthotopic mouse model. Total weight of metastatic lymph nodes was also reduced. In conclusion, NC-6301 with an optimized release rate improved the potency of DTX while reducing its toxicity.

Polymeric conjugates for drug delivery

The field of polymer therapeutics has evolved over the past decade and has resulted in the development of polymer-drug conjugates with a wide variety of architectures and chemical properties. Whereas traditional non-degradable polymeric carriers such as poly(ethylene glycol) (PEG) and N-(2-hydroxypropyl methacrylamide) (HPMA) copolymers have been translated to use in the clinic, functionalized polymer-drug conjugates are increasingly being utilized to obtain biodegradable, stimuli-sensitive, and targeted systems in an attempt to further enhance localized drug delivery and ease of elimination. In addition, the study of conjugates bearing both therapeutic and diagnostic agents has resulted in multifunctional carriers with the potential to both "see and treat" patients. In this paper, the rational design of polymer-drug conjugates will be discussed followed by a review of different classes of conjugates currently under investigation. The design and chemistry used for the synthesis of various conjugates will be presented with additional comments on their potential applications and current developmental status.

Protease-activated drug development

In this extensive review, we elucidate the importance of proteases and their role in drug development in various diseases with an emphasis on cancer. First, key proteases are introduced along with their function in disease progression. Next, we link these proteases as targets for the development of prodrugs and provide clinical examples of protease-activatable prodrugs. Finally, we provide significant design considerations needed for the development of the next generation protease-targeted and protease-activatable prodrugs.

Development of regional chemotherapies: feasibility, safety and efficacy in clinical use and preclinical studies

Conventional oral and intravenous chemotherapies permeate throughout the body, exposing healthy tissues to similar cytotoxic drug levels as tumors. This leads to significant dose-limiting toxicities that may prevent patients from receiving sufficient treatment to overcome cancers. Therefore, a number of locoregional drug-delivery strategies have been evaluated and implemented in preclinical studies, clinical trials and in practice, in the past decades to minimize systemic toxicities from chemotherapeutic agents and to improve treatment outcomes. Localized treatment is beneficial because many cancers, such as melanoma, peritoneal cancer and breast cancer, advance locally adjacent to the site of the primary tumors prior to their circulatory invasion. In this article, we will review the feasibility, safety and efficacy of multiple localized chemotherapies in clinical use and preclinical development.

Polypeptide conjugates of D-penicillamine and idarubicin for anticancer therapy

We investigated anticancer therapy with a novel combination of D-penicillamine (D-pen) and Idarubicin (Ida) in a synthetic dual drug conjugate (DDC). D-pen and Ida were covalently linked to poly(α)-L-glutamic acid (PGA) via reducible disulfide and acid-sensitive hydrazone bonds, respectively. The DDCs showed cell uptake and sustained release of the bound drugs in conditions mimicking the intracellular release media (10mM glutathione and pH 5.2). The in-vitro cytotoxicity of DDCs was comparable to unconjugated Ida in several sensitive and resistant cancer cell lines and correlated with the rate of cell uptake. In a single equivalent-dose pharmacokinetic study, DDCs enhanced the drug exposure by 7-fold and prolonged the plasma circulation half-life (t(1/2)) by 5-fold over unconjugated Ida. The therapeutic index of DDCs was 2-3-fold higher than unconjugated drugs. DDCs caused 89% tumor growth inhibition compared to 60% by unconjugated Ida alone and led to significant enhancement in the median survival (17%) of athymic nu/nu mice bearing NCI-H460 tumor xenografts.

Extravasation of polymeric nanomedicines across tumor vasculature

Tumor microvasculature is fraught with numerous physiological barriers which hinder the efficacy of anticancer agents. These barriers include chaotic blood supply, poor tumor vasculature permeability, limited transport across the interstitium due to high interstitial pressure and absence of lymphatic network. Abnormal microvasculature also leads to hypoxia and acidosis which limits effectiveness of chemotherapy. These barriers restrict drug or drug carrier extravasation which hampers tumor regression. Targeting key features of the tumor microenvironment such as tumor microvessels, interstitial hypertension and tumor pH is a promising approach to improving the efficacy of anticancer drugs. This review highlights the current knowledge on the distinct tumor microenvironment generated barriers which limit extravasation of drugs and focuses on modalities for overcoming these barriers using multi-functional polymeric carriers. Special attention is given to utilizing polymeric nanomedicines to facilitate extravasation of anticancer drugs for future cancer therapy.

Polymer therapeutics as nanomedicines: new perspectives

A growing number of polymer therapeutics have entered routine clinical use as nano-sized medicines. Early products were developed as anticancer agents, but treatments for a range of diseases and different routes of administration have followed--recently the PEGylated-anti-TNF Fab Cimzia® for rheumatoid arthritis and the PEG-aptamer Macugen® for age related macular degeneration. New polymer therapeutic concepts continue to emerge with a growing number of conjugates entering clinical development, for example PEGylated-aptamers and a polymer-based siRNA delivery system. 'Hot' topics of the past 2 years include; emerging issues relating to polymer safety, the increasing use of biodegradable polymers, design of technologies for combination therapy, potential biomarkers for patient individualisation of treatment and Regulatory challenges for 'follow-on/generic' polymer therapeutics.

Procoagulant inhibitory properties of paclitaxel poliglumex

Background

In Phase I evaluation of CT-2103 (paclitaxel poliglumex), prolongation of prothrombin time (PT) and activated thromboplastin time (aPTT) was observed, without clinical consequence, with doses 1.3–1.5 times higher than the current clinical dose of 175 mg/m². This Phase I, open-label, nonrandomized pilot study was performed to study the effect of the standard dose regimen on blood coagulation.

Methods

Seven previously treated solid tumor patients received CT-2103 175 mg/m² intravenously on day 1 of 21-day cycles for a mean of 5.4 cycles (median 4, range 2–14). Plasma samples were collected for cycle 1 predose and at hours 1, 24, 48, and 72 after the end of administration for drug levels, and for PT and aPTT assays.

Results

No coagulopathy-related adverse events were documented. Bleeding time remained normal in the six patients tested, with transient increases in PT and aPTT noted but resolving within 72 hours. Titration studies at 100 μg/mL of CT-2103 (corresponding to the standard clinical dose) prolonged PT and aPTT clotting times, produced a modest dose-dependent reduction of thrombin and factor Xa, and no significant changes in factors IXa, XIa, or XIIa. Two patients achieved stable disease for ≥10 cycles.

Conclusion

CT-2103 is associated with transient prolongation of PT and aPTT without clinical sequelae.

Polymer–drug conjugates for novel molecular targets

Polymer therapeutics can be already considered as a promising field in the human healthcare context. The discovery of the enhanced permeability and retention effect by Maeda, together with the modular model for the polymer–drug conjugate proposed by Ringsdorf, directed the early steps of polymer therapeutics towards cancer therapy. Orthodox anticancer drugs were preferentially chosen in the development of the first conjugates. The fast evolution of polymer chemistry and bioconjugation techniques, and a deeper understanding of cell biology has opened up exciting new challenges and opportunities. Four main directions have to be considered to develop this ‘platform technology’ further: the control of the synthetic process, the exhaustive characterization of the conjugate architectures, the conquest of combination therapy and the disclosure of new therapeutic targets. We illustrate in this article the exciting approaches offered by polymer–drug conjugates beyond classical cancer therapy, focusing on new, more effective and selective targets in cancer and in their use as treatments for other major human diseases.

Clinical developments in nanotechnology for cancer therapy

Nanoparticle approaches to drug delivery for cancer offer exciting and potentially "game-changing" ways to improve patient care and quality of life in numerous ways, such as reducing off-target toxicities by more selectively directing drug molecules to intracellular targets of cancer cells. Here, we focus on technologies being investigated clinically and discuss numerous types of therapeutic molecules that have been incorporated within nanostructured entities such as nanoparticles. The impacts of nanostructured therapeutics on efficacy and safety, including parameters like pharmacokinetics and biodistribution, are described for several drug molecules. Additionally, we discuss recent advances in the understanding of ligand-based targeting of nanoparticles, such as on receptor avidity and selectivity.

Combination therapy: opportunities and challenges for polymer-drug conjugates as anticancer nanomedicines

The discovery of new molecular targets and the subsequent development of novel anticancer agents are opening new possibilities for drug combination therapy as anticancer treatment. Polymer-drug conjugates are well established for the delivery of a single therapeutic agent, but only in very recent years their use has been extended to the delivery of multi-agent therapy. These early studies revealed the therapeutic potential of this application but raised new challenges (namely, drug loading and drugs ratio, characterisation, and development of suitable carriers) that need to be addressed for a successful optimisation of the system towards clinical applications.

Development of HPMA copolymer-anticancer conjugates: clinical experience and lessons learnt

The concept of polymer-drug conjugates was proposed more than 30 years ago, and an N-(2-hydroxypropyl)methacrylamide (HPMA) copolymer conjugate of doxorubicin covalently bound to the polymer backbone by a Gly-Phe-Leu-Gly peptidyl linker (FCE28068) became the first synthetic polymer-based anticancer conjugate to enter clinical trial in 1994. This conjugate arose from rational design attempting to capitalise on passive tumour targeting by the enhanced permeability and retention effect and, at the cellular level, lysosomotropic drug delivery to improve therapeutic index. Early clinical results were promising, confirming activity in chemotherapy refractory patients and the safety of HPMA as a new polymer platform. Subsequent Phase I/II trials have investigated an HPMA copolymer-based conjugate containing a doxorubicin and additionally galactose as a targeting moiety to promote liver targeting (FCE28069), and also HPMA copolymer conjugates of paclitaxel (PNU 166945), camptothecin (PNU 166148) and two platinates (AP5280 and AP5346- ProLindac). The preclinical and clinical observations made in these, and clinical studies with other polymer conjugates, should shape the development of next generation anticancer polymer therapeutics.

A Biodegradable Polymeric Carrier Based on PEG for Drug Delivery

A biodegradable copolymer (PEG- fum), based on poly(ethylene glycol) (PEG) and fumarate ( fum) units, was synthesized and studied as a drug carrier. PEG and fum were linked together by ester bonds to confer biodegradability to the polymeric backbone in vivo. Hence, this copolymer can be used with molecular weights above the kidney clearance threshold for PEG without body accumulation. The PEG- fum was designed to be a high drug loading carrier due to the fumarate units, thus, overcoming the limitations of linear PEGs. Suitable reactive groups for drug coupling were added by reacting fumarate with tioglycolic acid (TGA). The pendant TGA carboxylic groups were conjugated to the camptothecin derivative, SN38, taxol, and epirubicin. The SN38 and taxol linked to the PEG- fum-(TGA) increased their solubility 15- and 100-fold, respectively. The rate of SN38 release in plasma was adequate for prolonged circulation n vivoi, while taxol was rapidly hydrolyzed. This relatively fast degradation could hamper the conjugate from accumulating in the tumor tissue by enhanced permeability and retention effect (EPR). Instead, EPR effect could be exploited with the epirubicin conjugate coupled by means of a hydrazone bond. This linkage provides good blood stability, while readily cleaved in acidic environment like those in endosomes and lysosomes. Therefore, the drug is released intercellularly in its active form only after, thus reducing toxic effects.

Paclitaxel poliglumex and carboplatin as first-line therapy in ovarian, peritoneal or fallopian tube cancer: a phase I and feasibility trial of the Gynecologic Oncology Group

PURPOSE

To estimate the maximum tolerated dose (MTD) of paclitaxel poliglumex (PPX) in combination with carboplatin in patients with chemotherapy-naive ovarian, primary peritoneal or fallopian tube cancer, and to assess the feasibility of administering multiple cycles of this regimen.

METHODS

The first 11 patients were treated in a standard 3 + 3 dose-seeking design, with carboplatin held constant at area under the curve (AUC) of 6 and PPX at 225, 175 or 135 mg/m(2). Pharmacokinetics of PPX and carboplatin were evaluated during this dose-seeking component of the trial. MTD was defined by acute dose-limiting toxicities (DLT) in the first cycle. Twenty additional evaluable patients were treated at the estimated MTD to assess the feasibility of this regimen over >or=4cycles.

RESULTS

PPX at 225 mg/m(2) resulted in DLT in 2/3 patients, and was de-escalated first to 175 mg/m(2) and then to 135 mg/m(2). PPX slowly hydrolyzed to paclitaxel and did not alter the pharmacokinetics of carboplatin. DLT within the first 4-cycles were observed in 3 patients (15%) treated at the MTD: neutropenia > 2weeks (2), febrile neutropenia (1). Nineteen patients (95%) experienced grade 4 neutropenia. Sixteen patients (80%) had at least one episode of grade 3 thrombocytopenia. Three patients (15%) had grade 2 and one had grade 3 peripheral neuropathy. Complete response by CA-125 was 75%.

CONCLUSIONS

The recommended dose of PPX of 135 mg/m(2) with carboplatin (AUC = 6) in newly diagnosed ovarian cancer was feasible for multiple cycles, but hematologic toxicity was greater compared with standard carboplatin and 3-hour paclitaxel.

Design, synthesis and applications of hyaluronic acid-paclitaxel bioconjugates

Paclitaxel (1a), a well known antitumor agent adopted mainly for the treatment of breast and ovarian cancer, suffers from significant disadvantages such as low solubility, certain toxicity and specific drug-resistance of some tumor cells. To overcome these problems extensive research has been carried out. Among the various proposed strategies, the conjugation of paclitaxel (1a) to a biocompatible polymer, such as hyaluronic acid (HA, 2), has also been considered. Coupling a bioactive compound to a biocompatible polymer offers, in general, many advantages such as better drug solubilization, better stabilization, specific localization and controlled release. Hereafter the design, synthesis and applications of hyaluronic acid-paclitaxel bioconjugates are reviewed. An overview of HA-paclitaxel combinations is also given.

Therapeutic potential of AIF-mediated caspase-independent programmed cell death

Resistance to anticancer drugs is often related to deficient cell death execution pathways in cancer cells. Apoptosis, which denotes a form of cell death executed by caspases, was traditionally considered as the only physiological and programmed form of cell death. However, recent evidence indicates that programmed cell death (PCD) can occur in complete absence of caspase activation. Indeed, a large number of caspase-independent models are now defined and a key protein implicated in this type of PCD, apoptosis-inducing factor (AIF), has been identified. AIF is a mitochondrial protein with two faces looking in opposite life/death directions. Recently, the identification of five different isoforms allowed a better characterization of AIFs life/mitochondrial versus death/nuclear functions, as well as definition of its pro-apoptotic region and some of its nuclear partners. Importantly, much work on caspase-independent PCD has revealed that AIF participates in more PCD systems than initially thought. A wider molecular knowledge of AIF, and of the caspase-independent PCDs in which it is involved, are key to provide new insights into the role of PCD. There is no doubt that these insights will lead to the development of more selective and efficient drugs against cancer, degenerative diseases, and other pathological disorders implicating AIF.